1. Field of the Invention
The invention refers, as set out in the description of this report, to a gypsum mortar with expanded vermiculite and enhanced with tartaric acid, citric acid, copper sulphate and potassium or sodium citrate aimed for construction, and the procedure to obtain this.
More specifically, the purpose of the invention consists of a modified calcium sulphate mortar which presents the special feature of incorporating expanded vermiculite achieved in a completely different way to those on the market. When we incorporate the calcium sulphate and water and enhance the mixture with tartaric acid, citric acid, copper sulphate and potassium or sodium citrate we obtain a mortar specially designed for fire-resistant applications and for thermal and acoustic insulations; these have the special feature of some excellent mechanical properties which makes it unnecessary to subsequently process finishings with sheets together with the corresponding sealing of joints and application of a metallic periphery. Given its excellent properties, this is also applicable to the manufacture of sheets for coating by a plaster cast system; these are either smooth or with decorative motifs.
The field of application of this invention is framed as gypsum mortar in the materials sector for coating of surfaces, more specifically within passive fire protection systems; it is also classified under acoustic and thermal insulations and decorative coatings.
2. Description of the Related Art
As is known, very different mortars of all kinds of vermiculite are reputed in the sector. The main shortcoming of these mortars, however, is the lack of mechanical resistance for which reason they tend to deteriorate much more because of friction and require subsequent finishings with fire-resistant covering panels. They will also need periodic maintenance, which corrects imperfections which occur in the mortar over time. As for acoustic or thermal insulations, these vermiculite mortars also have to be accompanied by rock wool or similar finishings or insulating sheets. In addition, all these kinds of finishings require performing additional work such as sealing joints, installing a metallic periphery, etc; it is therefore desirable to have a mortar which complies with all the functions mentioned in one sole direct application without the need for subsequent processing.
Vermiculite mortars to date incorporate expanded vermiculite by means of the simple process of heating the mineral in a furnace up to 870° C.; at this temperature the material laminates and expands up to 20 times its volume as the water in the mineral evaporates and this turns into bellows with sheets which produce brownish-grey highlights. The sheets formed act as tiny “mirrors” which reflect both thermal radiation and sound waves, which gives the mortar its insulating and fire-resistant properties. In the processes known to date, the crude vermiculite is placed inside furnaces by means of a horizontal conveyor belt; four different kinds of expanded vermiculite come out with different grain size and certain physical properties. By means of the new system proposed by the inventor, the process is performed by means of a furnace which transports the vermiculite vertically to perform the process in a similar way as is traditionally carried out with perlite. By means of this vertical process we obtain more vermiculite than by the traditional method; this new vermiculite is what gives the mortar the characteristics indicated in this report.
Another special feature presented by the mortar is that, unlike traditional mortars, the enhancer is not included in the dry mass but rather the water has to be enhanced before adding this to the mixture of sulphate and vermiculite.
The use of enhancers comprised of various products which make up this mortar's enhancer is also known; for example the citric acid and tartaric acid widely used to manufacture traditional enhancers. However, the proportions used in this mortar together with the use of substances not used in reputed enhancers give the resulting mortar better adherence, malleability, and control of hardening. We are aware of some documents, which incorporate the use of citric or tartaric acid such as patent ES 2233197 relating to an enhancer for gypsum mortar. However, as any expert on the matter can understand, this is incorporated in different proportions and uses other substances as an enhancer for gypsum mortars and aimed at applications different to those of the invention at issue here.
We should also mention the following as documents of interest related to this invention:                Patent ES 2169605, referring to gypsum mortar whose composition includes citric acid, citrates, tartaric acid or tartrates.        Patent ES 2103417, relating to a dry mortar mixture to be enhanced with gypsum mortar and limestone.        Patent ES 2129164 on a dry mortar for coating made of gypsum mortar or baked gypsum mortar based on a granulate of impregnated cellular concrete.        Patent ES 513917 dealing with a procedure to prepare a fire-resistant mortar comprised of semi-hydrated calcium sulphate in the form of gypsum mortar.        Patent No. 3827895 referring to a composition to be used in construction containing 15% to 20% of gypsum mortar.        Patent GB 1258054 relating to some concrete production improvements including gypsum mortar in its composition.        
However, although the aforementioned documents refer to mortars for construction whose compositions include some of the components of the invention proposed, none of them include all of these nor do they apply a similar procedure; it can therefore be pointed out that we know of no other invention, which presents some characteristics similar to those of the invention mentioned here.
Other documents describing the closest subject matter provide for a number of more or less complicated features that fail to solve the problem in an efficient and economical way. None of these patents suggest the novel features of the present invention.